I was sorry to see the Playhouse rather less than half full for Music Theatre Wales’s production – hotfoot from its premiere at Covent Garden’s Linbury Studio – of Letters of a Love Betrayed, an opera by composer Eleanor Alberga and librettist Donald Sturrock based on a short story by Isabel Allende. The poor attendance was no doubt partly a consequence of the disinclination of theatre-goers to turn out on a Sunday evening, though a suspicion that this new work might prove inaccessible perhaps had an influence too.

In the event, there proved to be nothing in the slightest bit ‘difficult’ about the piece. The story it tells is lucid and gripping, focusing on a girl (the excellent Mary Plazas, pictured with Erwan Hughes) orphaned in childhood who grows up to find a grasping uncle (Jonathan May) trying to chisel her out of her estate.

At first, he tries to persuade her to remain in the convent, where she has been brought up, and let him look after the land. When she rumbles this scheme, he tries a second approach to the problem by persuading his son (Christopher Steele) to marry her. A succession of beautifully phrased letters he sends to her do the trick; they are received by her in a rapture reminiscent – inevitably perhaps – of that experienced by Tatiana in the sending of her fateful letter in Eugene Onegin. Sadly, the inspiring individual who captivates her with his writing is transformed into a drunken, violent, womanising rotter when their shared life begins.

The tortured, tangled emotions on display are eloquently reflected – arguably sometimes at too great a length – in Ms Alberga’s music, which was ably interpreted by the singers and a 14-strong orchestra under conductor Michael Rafferty. Occasional flourishes of guitar and percussion serve to remind us of the South American setting, whose mountain scenery is suggested in soaring flights from flute and piccolo. A slightly jarring note is struck, however, with tuneful folk ditties that sit uneasily with the rest of the score.